Wound debridement by irrigation with ultrasonically activated microbubbles

ABSTRACT

A treatment system for debriding a treatment area of a tissue site and applying negative pressure is disclosed. In some embodiments, the treatment system may include an ultrasonic bubble generator fluidly coupled to a negative-pressure source, fluid source, and a dressing. Fluid may be drawn from the fluid source to the ultrasonic bubble generator, whereby micro-bubbles and ultrasonic waves may be generated in the fluid before the fluid is instilled to the dressing.

RELATED APPLICATIONS

The present invention is a continuation of U.S. patent application Ser.No. 16/595,763, filed Oct. 8, 2019, which is a continuation of U.S.patent application Ser. No. 15/147,666, filed May 5, 2016, now U.S. Pat.No. 10,471,190, which claims the benefit under 35 U.S.C. § 119(e), ofthe filing of U.S. Provisional Patent Application Ser. No. 62/158,630,filed May 8, 2015, all of which are incorporated herein by reference forall purposes.

TECHNICAL FIELD

The invention set forth in the appended claims relates generally totissue treatment systems and more particularly, but without limitation,to debridement devices, systems, and methods suitable for debriding atissue site.

BACKGROUND

Clinical studies and practice have shown that reducing pressure inproximity to a tissue site can augment and accelerate growth of newtissue at the tissue site. The applications of this phenomenon arenumerous, but it has proven particularly advantageous for treatingwounds. Regardless of the etiology of a wound, whether trauma, surgery,or another cause, proper care of a wound is important to the outcome.Treatment of wounds or other tissue with reduced pressure may becommonly referred to as “negative-pressure therapy,” but is also knownby other names, including “negative-pressure wound therapy,”“reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,”and “topical negative-pressure,” for example. Negative-pressure therapymay provide a number of benefits, including migration of epithelial andsubcutaneous tissues, improved blood flow, and micro-deformation oftissue at a wound site. Together, these benefits can increasedevelopment of granulation tissue and reduce healing times.

There is also widespread acceptance that debridement of a tissue sitecan be highly beneficial for new tissue growth. Debridement may refer toa process for removing dead, damaged, or infected tissue from a tissuesite for improving the healing potential of healthy tissue remaining atthe tissue site. Several factors may make proper debridement difficult,such as challenging wound locations, immobile patients, andenvironmental constraints. Further, debridement may often be painful forthe patient, and in some circumstances may also require a high level ofskill from the caregiver, thereby presenting additional challenges.Additionally, debridement methods that are less painful to patients maybe relatively slow processes. Therefore, improvements to debridementdevices, systems, and methods that may reduce the amount of time todebride a tissue site as well as reduce the risks of pain for thepatient or damage to healthy tissue associated with conventionalmethodologies may be desirable.

BRIEF SUMMARY

New and useful systems, apparatuses, and methods for debriding a tissuesite are set forth in the appended claims. Illustrative embodiments arealso provided to enable a person skilled in the art to make and use theclaimed subject matter.

In some embodiments, a system for treating a tissue site may include adressing, a negative-pressure source fluidly coupled to the dressing, afluid source, and an ultrasonic bubble generator. The ultrasonic bubblegenerator may be fluidly coupled to the fluid source and to the dressingand may be configured to generate micro-bubbles and ultrasonic waves ina fluid from the fluid source.

In other embodiments, a method for debriding necrotic tissue from atissue site may include coupling a fluid source to the tissue site,supplying a fluid from the fluid source to an ultrasonic bubblegenerator, generating micro-bubbles and ultrasonic waves in the fluidwith the ultrasonic bubble generator, and delivering the micro-bubblesand ultrasonic waves to the necrotic tissue. The ultrasonic bubblegenerator may further include an ultra-violet light source. In someembodiments, the method may further include coupling a negative-pressuresource to a dressing.

Other aspects, features, and advantages of the illustrative embodimentswill become apparent with reference to the drawings and detaileddescription that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an example embodiment ofnegative-pressure therapy system that can deliverultrasonically-activated micro-bubbles in accordance with thisspecification; and

FIG. 2 is a perspective view illustrating additional details that may beassociated with some example embodiments of the negative-pressuretherapy system of FIG. 1 .

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides informationthat enables a person skilled in the art to make and use the subjectmatter set forth in the appended claims, but may omit certain detailsalready well-known in the art. The following detailed description is,therefore, to be taken as illustrative and not limiting.

The example embodiments may also be described herein with reference tospatial relationships between various elements or to the spatialorientation of various elements depicted in the attached drawings. Ingeneral, such relationships or orientation assume a frame of referenceconsistent with or relative to a patient in a position to receivetreatment. However, as should be recognized by those skilled in the art,this frame of reference is merely a descriptive expedient rather than astrict prescription.

Referring now primarily to FIG. 1 , a therapy system 100 that canprovide negative-pressure therapy with instillation of topical treatmentsolutions for treating a tissue site 102 is presented. The tissue site102 may include, without limitation, any irregularity with a tissue,such as an open wound, surgical incision, or diseased tissue. Thetherapy system 100 is presented in the context of a tissue site 102 thatincludes a wound 104, which is through the epidermis 106, or generallyskin, and the dermis 108 and reaching into a hypodermis, or subcutaneoustissue 110. The therapy system 100 may be used to treat a wound of anydepth, as well as many different types of wounds including open woundsor other tissue sites. The tissue site 102 may be the bodily tissue ofany human, animal, or other organism, including bone tissue, adiposetissue, muscle tissue, dermal tissue, vascular tissue, connectivetissue, cartilage, tendons, ligaments, or any other tissue. Treatment ofthe tissue site 102 may include removal of fluids, for example, exudateor ascites.

The term “tissue site” in this context broadly refers to a wound ordefect located on or within tissue, including but not limited to, bonetissue, adipose tissue, muscle tissue, neural tissue, dermal tissue,vascular tissue, connective tissue, cartilage, tendons, or ligaments. Awound may include chronic, acute, traumatic, subacute, and dehiscedwounds, partial-thickness burns, ulcers (such as diabetic, pressure, orvenous insufficiency ulcers), flaps, and grafts, for example. The term“tissue site” may also refer to areas of any tissue that are notnecessarily wounded or defective, but are instead areas in which it maybe desirable to add or promote the growth of additional tissue. Forexample, negative pressure may be used in certain tissue areas to growadditional tissue that may be harvested and transplanted to anothertissue location.

As used herein, the terms “debride,” “debriding,” and “debridement,”relate to the act of removing or the removal of undesirable tissue, suchas, eschar, necrotic, damaged, infected, contaminated, or adherenttissue, or foreign material from a tissue site. Several methods ofdebridement may be employed to treat a wound 104 having necrotic tissue112, including surgical debridement, mechanical debridement, chemical orenzymatic debridement, and autolytic debridement.

However, each of these methods has both advantages and disadvantages.For example, while mechanical debridement is perhaps the fastest methodof debridement, it is almost invariably painful or at least submits thepatient to a significant level of discomfort. Additionally, mechanicaldebridement typically requires a high level of skill from the caregiver.

Chemical, or enzymatic, debridement entails the use of chemical enzymesto convert the necrotic tissue to slough. Chemical debridement may befast-acting and cause minimal damage to healthy tissue if the chemicalsare applied properly. However, chemical debridement has disadvantages aswell. The process may be expensive and traditional chemical debridementmethods and systems, such as low pH systems, may be painful to apatient. Other debriding agents, such as papain, may have other healthimplications and only have limited usage that is restricted by law.Other agents may be used, such as medical grade honey, but can becomequickly mobile in the presence of fluid, such as wound exudate, and anapplied negative pressure.

Autolytic debridement, or autolysis, entails the use of the body's ownenzymes and white blood cells, along with moisture, to hydrate andliquefy the necrotic tissue 112 and slough. Since autolytic debridementis a naturally occurring process, it is relatively painless and does notrisk damage to healthy tissue. Further, autolytic debridement does notrequire wound fluid to remain in contact with the necrotic tissue 112,and can be facilitated by the use of films, hydrocolloids, andhydrogels. A disadvantage of autolytic debridement is that autolyticdebridement is slower than other types of debridement, rendering thewound susceptible to infection.

Thus, there is a need for a debriding process that accelerates, andthereby enhances, the naturally-occurring debridement process withoutthe disadvantages associated with mechanical debridement, while also notusing enzymes or other chemicals or drugs. Moreover, it is desirable tohave a system and method that allow negative-pressure treatment tooccur. As disclosed herein, the therapy system 100 may address theseoutstanding needs and others. For example, the therapy system 100 mayprovide a low-pain alternative for enhanced debridement and healing ofwounds that can be used in conjunction with negative-pressure treatment.

Referring again to FIG. 1 , the wound 104 may include necrotic tissue112, and in many instances, it may be desirable to remove the necrotictissue 112 in order to promote healing of the wound 104. Theillustrative, non-limiting embodiment shows the therapy system 100 inthe context of the wound 104 having a localized, or discrete area, ofnecrotic tissue 112 within the wound. The therapy system 100 may be usedin broader contexts, including with any tissue site having undesirabletissue. Such undesirable tissue may include, necrotic, damaged,infected, contaminated, or adherent tissue, foreign material within thewound 104, and may include a layer of necrotic tissue 112 that coversthe entire surface of the wound 104.

The therapy system 100 may include a dressing, a negative-pressuresource, a fluid source, and a micro-bubble source. For example, adressing 114 may be fluidly coupled to a negative-pressure source 116, afluid source 117, and a micro-bubble subsystem 118, as illustrated inFIG. 1 . The therapy system 100 may also include a container forsupplying fluid as well as collecting exudates, such as a container 120,coupled to the dressing 114 and to the negative-pressure source 116.

In general, components of the therapy system 100 may be coupled directlyor indirectly. For example, the negative-pressure source 116 may bedirectly coupled to components of the micro-bubble subsystem 118 and thecontainer 120, and indirectly coupled to the dressing 114 through themicro-bubble subsystem 118 and the container 120. In some embodiments,components may be coupled by virtue of physical proximity, beingintegral to a single structure, or being formed from the same piece ofmaterial. Coupling may also include mechanical, thermal, electrical, orchemical coupling (such as a chemical bond) in some contexts.

Components may also be fluidly coupled to each other to provide a pathfor transferring fluids (i.e., liquid and/or gas) between thecomponents. In some embodiments, for example, components may be fluidlycoupled through a tube. A “tube,” as used herein, broadly refers to atube, pipe, hose, conduit, or other fluid conductor with one or morelumina adapted to convey fluid between two ends. Typically, a tube is anelongated, cylindrical structure with some flexibility, but the geometryand rigidity may vary. A fluid conductor may also be integrally moldedinto a component in some embodiments.

The dressing 114 may be placed within, over, on, or otherwise proximateto the tissue site 102. The dressing 114 may be sealed to tissue nearthe tissue site 102. For example, the dressing 114 may be sealed toundamaged epidermis peripheral to the tissue site 102. Thus, thedressing 114 can provide a sealed therapeutic environment proximate tothe tissue site 102, substantially isolated from the externalenvironment, and the negative-pressure source 116 can reduce thepressure in the sealed therapeutic environment. Negative pressureapplied across the tissue site 102 through the dressing 114 in thesealed therapeutic environment can induce macro-strain and micro-strainin the tissue site, as well as remove exudate and other fluid from thetissue site 102, which can be collected in the container 120.

The fluid mechanics of using a negative-pressure source to reducepressure in another component or location, such as within a sealedtherapeutic environment, can be mathematically complex. However, thebasic principles of fluid mechanics applicable to negative-pressuretherapy and instillation are generally well-known to those skilled inthe art.

In general, fluid flows toward lower pressure along a fluid path. Thus,the term “downstream” typically implies something in a fluid pathrelatively closer to a source of negative pressure or further away froma source of positive pressure; conversely, the term “upstream” impliessomething relatively further away from a source of negative pressure orcloser to a source of positive pressure. Similarly, it may be convenientto describe certain features in terms of fluid “inlet” or “outlet” insuch a frame of reference, and the process of reducing pressure may bedescribed illustratively herein as “delivering,” “distributing,” or“generating” reduced pressure, for example. This orientation isgenerally presumed for purposes of describing various features andcomponents herein.

“Negative pressure” generally refers to a pressure less than a localambient pressure, such as the ambient pressure in a local environmentexternal to a sealed therapeutic environment provided by the dressing114. In many cases, the local ambient pressure may also be theatmospheric pressure at which a tissue site is located. Alternatively,negative pressure may be a pressure less than a hydrostatic pressureassociated with tissue at the tissue site. Unless otherwise indicated,values of pressure stated herein are gauge pressures. Similarly,references to increases in negative pressure typically refer to adecrease in absolute pressure, while decreases in negative pressuretypically refer to an increase in absolute pressure.

A negative-pressure source, such as the negative-pressure source 116,may be a reservoir of air at a negative pressure, or may be a manual orelectrically-powered device that can reduce the pressure in a sealedvolume, such as a vacuum pump, a suction pump, a wall suction portavailable at many healthcare facilities, or a micro-pump, for example. Anegative-pressure source may be housed within or used in conjunctionwith other components, such as sensors, processing units, alarmindicators, memory, databases, software, display devices, or userinterfaces that further facilitate negative-pressure therapy. While theamount and nature of negative pressure applied to a tissue site may varyaccording to therapeutic requirements, the pressure is generally a lowvacuum, also commonly referred to as a rough vacuum, between −5 mm Hg(−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges arebetween −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa).

The fluid source 117 may be housed within or used in conjunction withother components to facilitate movement of a fluid. The fluid source 117may be a fluid pump, for example a peristaltic pump. Alternatively, insome embodiments, the fluid source 117 may be a fluid reservoir, whichmay store and deliver fluid. In any embodiment, the fluid source 117,such as a fluid pump or a fluid reservoir, may include a container, suchas a canister, pouch, or other storage component. In some embodimentsthe fluid source 117 may be a fluid pump that helps supply themicro-bubble subsystem 118 with the fluid that may ultimately bedelivered to a tissue site.

The dressing 114 may include a manifold 122 and a drape 124. Thedressing 114 may also include an attachment device 126 that affixes thedrape 124 to the epidermis 106 of the patient. The drape 124 may alsoinclude an adhesive surface that seals directly against the epidermis106 of the patient without the need for an attachment device. Themanifold 122 may be positioned between a tissue-facing surface of thedrape 124 and the tissue site 102.

The manifold 122 may generally include any substance or structureproviding a plurality of pathways adapted to collect or distribute fluidacross a tissue site. For example, a manifold may be adapted to receivenegative pressure from a source and distribute negative pressure throughmultiple apertures across a tissue site, which may have the effect ofcollecting fluid from across a tissue site and drawing the fluid towardthe source. In some embodiments, the fluid path may be reversed or asecondary fluid path may be provided to facilitate distributing fluidacross a tissue site.

In some illustrative embodiments, the pathways of a manifold may beinterconnected to improve distribution or collection of fluids across atissue site. For example, cellular foam, open-cell foam, reticulatedfoam, porous tissue collections, and other porous material such as gauzeor felted mat generally include pores, edges, and/or walls adapted toform interconnected fluid pathways. Liquids, gels, and other foams mayalso include or be cured to include apertures and fluid pathways. Insome illustrative embodiments, a manifold may be a porous foam materialhaving interconnected cells or pores adapted to distribute negativepressure across a tissue site. The foam material may be eitherhydrophobic or hydrophilic. The pore size of a foam material may varyaccording to needs of a prescribed therapy. For example, in someembodiments, the manifold 122 may include a wound filler, which may be afoam having a large pore size or may be a perforated felted foam. Thepores or perforations of the wound filler may be in the range of 3-7millimeters (mm) in diameter, and preferably about 5 mm in diameter. Thetensile strength of the manifold 122 may also vary according to needs ofa prescribed therapy. For example, the tensile strength of a foam may beincreased for instillation of topical treatment solutions. In onenon-limiting example, the manifold 122 may be an open-cell, reticulatedpolyurethane foam such as GranuFoam® dressing available from KineticConcepts, Inc. of San Antonio, Tex.; in other embodiments the manifold122 may be an open-cell, reticulated polyurethane foam such as aVeraFlo® foam, also available from Kinetic Concepts, Inc., of SanAntonio, Tex.

In an example in which the manifold 122 may be made from a hydrophilicmaterial, the manifold 122 may also wick fluid away from a tissue site,while continuing to distribute negative pressure to the tissue site. Thewicking properties of the manifold 122 may draw fluid away from a tissuesite by capillary flow or other wicking mechanisms. An example of ahydrophilic foam is a polyvinyl alcohol, open-cell foam such as V.A.C.WhiteFoam® dressing available from Kinetic Concepts, Inc. of SanAntonio, Tex. Other hydrophilic foams may include those made frompolyether. Other foams that may exhibit hydrophilic characteristicsinclude hydrophobic foams that have been treated or coated to providehydrophilicity.

In some embodiments, the manifold 122 may be constructed frombioresorbable materials. Suitable bioresorbable materials may include,without limitation, a polymeric blend of polylactic acid (PLA) andpolyglycolic acid (PGA). The polymeric blend may also include withoutlimitation polycarbonates, polyfumarates, and capralactones. Themanifold 122 may further serve as a scaffold for new cell-growth, or ascaffold material may be used in conjunction with the manifold 122 topromote cell-growth. A scaffold is generally a substance or structureused to enhance or promote the growth of cells or formation of tissue,such as a three-dimensional porous structure that provides a templatefor cell growth. Illustrative examples of scaffold materials includecalcium phosphate, collagen, PLA/PGA, coral hydroxy apatites,carbonates, or processed allograft materials.

In some embodiments, the drape 124 may provide a bacterial barrier andprotection from physical trauma. The drape 124 may also be constructedfrom a material that can reduce evaporative losses and provide a fluidseal between two components or two environments, such as between atherapeutic environment and a local external environment. The drape 124may be, for example, an elastomeric film or membrane that can provide aseal adequate to maintain a negative pressure at a tissue site for agiven negative-pressure source. In some example embodiments, the drape124 may be a polymer drape, such as a polyurethane film, that ispermeable to water vapor but impermeable to liquid. Such drapestypically have a thickness in the range of 25-50 microns. For permeablematerials, the permeability generally should be low enough that adesired negative pressure may be maintained.

In some embodiments, an attachment device 126 may be used to attach thedrape 124 to an attachment surface, such as undamaged epidermis, agasket, or another cover. The attachment device 126 may take many forms.For example, an attachment device may be a medically-acceptable,pressure-sensitive adhesive that extends about a periphery, a portion,or the entire drape 124. In some embodiments, for example, some or allof the drape 124 may be coated with an acrylic adhesive having a coatingweight between 25-65 grams per square meter (g.s.m.). Thicker adhesives,or combinations of adhesives, may be applied in some embodiments toimprove the seal and reduce leaks. Other example embodiments of anattachment device may include a double-sided tape, paste, hydrocolloid,hydrogel, silicone gel, or organogel.

The negative pressure provided by the negative-pressure source 116 maybe delivered through a conduit 128 to a negative-pressure interface 130,which may be an elbow port 132. In one illustrative embodiment, thenegative-pressure interface 130 is a T.R.A.C.® Pad or Sensa T.R.A.C.®Pad available from KCI of San Antonio, Tex. The negative-pressureinterface 130 allows the negative pressure to be delivered to the drape124 and realized within an interior portion of the drape 124 and themanifold 122. In this illustrative, non-limiting embodiment, the elbowport 132 extends through the drape 124 to the manifold 122, but numerousarrangements are possible.

The container 120 is representative of a container, canister, pouch, orother storage component, which can be used to manage exudate and otherfluid withdrawn from a tissue site. In many environments, a rigidcontainer may be preferred or required for collecting, storing, anddisposing of fluid. In some preferred embodiments, the container 120 maybe positioned in fluid communication between the negative-pressuresource 116 and the dressing 114 to collect fluid drawn from a tissuesite. The container 120 may also include features that enable filteringof the effluent that is withdrawn from the dressing 114 and tissue site102. In some embodiments, the container 120 may attach to thenegative-pressure source 116, as illustrated in FIG. 1 .

The container 120 may include multiple ports and connection interfacesfor integration with the negative-pressure source 116, the fluid source117, and the other components of the therapy system 100. For example,the container 120 may have two outlets, one of which may be for fluidlyconnecting the container 120 to the fluid source 117, and the second ofwhich may be for fluidly connecting the container 120 to thenegative-pressure source 116.

The micro-bubble subsystem 118 may include a UV light sterilizer 136 andan ultrasonic bubble generator 138. The UV light sterilizer 136 may bepositioned in fluid connection between the negative-pressure source 116and the ultrasonic bubble generator 138. In some embodiments, themicro-bubble subsystem 118 may be fluidly connected to thenegative-pressure source 116 and the dressing 114 by the supply conduit140. In some embodiments, the micro-bubble subsystem 118 may be in closephysical proximity to the dressing 114, or optionally incorporated aspart of the dressing 114. In other embodiments, some or all of thecomponents of the micro-bubble subsystem 118 may be incorporated withinthe negative-pressure source 116.

As fluid is moved from the negative-pressure source 116 through thesupply conduit 140 to the ultrasonic bubble generator 138, the fluid maypass through the UV light sterilizer 136. The UV light sterilizer 136may contain a UV light source, which may dose the fluid passing throughthe UV light sterilizer 136 with UV light to kill any pathogens that maybe in the fluid. Once the fluid has passed through the UV lightsterilizer 136, the fluid may be delivered to the ultrasonic bubblegenerator 138 through supply conduit 140.

The ultrasonic bubble generator 138 may function to generate bothmicro-bubbles and an ultrasonic waveform in a fluid. For example, theultrasonic bubble generator 138 may be an apparatus for generating anoutput flow of liquid, including an acoustic transducer for introducingacoustic energy into the liquid and a gas bubble generator forgenerating gas bubbles within the liquid, as described in U.S. PatentApplication Publication No. US 2012/0227761 A1, which is herebyincorporated by reference in its entirety. As illustrated in FIG. 1 ,fluid may be delivered from the UV light sterilizer 136 through supplyconduit 140 to the ultrasonic bubble generator 138. As the fluid passesthrough the ultrasonic bubble generator 138, the ultrasonic bubblegenerator 138 may generate and inject gas bubbles within the fluid.While the micro-bubbles may be generated in a range of sizes, themicro-bubbles may typically be approximately 15-200 micrometers (μm) indiameter. The ultrasonic bubble generator 138 may then generate anultrasonic waveform that may be conducted through the fluid as it flowsthrough the ultrasonic bubble generator 138. In some embodiments, theultrasonic bubble generator 138 may include a transducer that emitsacoustic energy. The acoustic energy may be emitted as intermittentpulses. Referring also to FIG. 2 , as micro-bubbles 202 are hit by theultrasonic waves, the micro-bubbles may undergo significant deformationwhich may manifest itself as a ripple 204 at the gas/liquid interface.As a result of this ripple, the micro-bubble can exert a scrubbingaction on surfaces it touches as the micro-bubble 206 is deformed, andthe turbulence formed around the micro-bubble may also cause themicro-bubble to be drawn to surfaces and into cracks and crevices, suchas deformities at a tissue site.

In some embodiments, the manifold 122 may be tailored to cause minimalattenuation of the ultrasonic energy generated by the micro-bubblesource 118. For example, the manifold 122 may be largely constructedfrom polymers that are hydrophilic, which may contain water or beconfigured to absorb water. Such hydrophilic polymers may include polyhydroxy ethyl methacrylate, copolymer of N-vinyl pyrrolidone and2-hydroxy ethyl methacrylate, terpolymer based on glycerol methacrylate,copolymer of N-vinyl pyrrolidone and methyl methacrylate, as well aspolymethyl methacrylate (PMMA). Additionally, the manifold 122 may beconstructed from hydrophilic polyurethane polymers, such as TECOPHILIChydrophilic polyurethanes available from The Lubrizol Corp. ofWickliffe, Ohio, which in extrusion grade formulations, may absorb waterup to 100% of the weight of dry resin (900% of weight of dry resin forhydrogel grades) while retaining structural integrity. In someembodiments, the manifold 122 may be formed from one of the hydrophilicpolymers listed above into a porous or foamed structure with poresmeasuring approximately 5-10 mm in diameter, which may minimize thenumber of struts that could interfere with the passage of bubbles. Inother embodiments, the manifold 122 may be formed from one of thehydrophilic polymers formed into a perforated sheet having protrusionson one side. In some instances, the protrusions may be spaced about 5-10mm apart from each other, and may be hemispherical or polygonal inshape. The protrusions may act as spacers between the wound 104 and thedrape 124.

The therapy system 100 presented in FIG. 1 may also include a secondinterface, such as fluid-delivery interface 142. The fluid-deliveryinterface 142 may be fluidly coupled to the dressing 114 and may passthrough a hole cut in the drape 124. The hole cut in the drape for thefluid-delivery interface 142 may be separated as far apart as possiblefrom the location or other hole cut in the drape through which thenegative-pressure interface 130 may pass. The fluid-delivery interface142 may allow for a fluid to be delivered by the therapy system 100through the drape 124 and to the manifold 122 and the tissue site 102.

In some embodiments, the fluid-delivery interface 142 may include aninlet pad. The inlet pad may be a non-dampening material or a materialthat is not sound-absorbing. In some embodiments, the inlet pad may bean elastomer. For example, the inlet pad may be an elastic polymer, suchas polyurethane, thermoplastic elastomers, polyether block amide(PEBAX), polyisoprene, polychloroprene, chlorosulphonated polythene, andpolyisobutylene, blends and copolymers.

The composition of the fluid may vary according to a prescribed therapy,but examples of solutions that may be suitable for some prescriptionsinclude a saline solution with a low level of surfactant, such as <0.1%,and more typically 0.015%. Such surfactants may include Pluronic F68,polyolefin oxides, and polyolefin glycols. By including a surfactant inthe fluid, the generated micro-bubbles may be preserved for a longerduration as they travel from the ultrasonic bubble generator 138 to thetissue site 102.

The therapy system 100 may also include a particulate filter 134, whichmay be positioned in fluid communication between the container 120and/or the negative-pressure source 116 and the dressing 114. Theparticulate filter 134 may function to remove particulate matter fromthe effluent that has circulated through the dressing 114. For example,in the embodiment pictured in FIG. 1 , fluid delivered to the dressing114 and to the tissue site 102 may be drawn out of the dressing 114through the negative-pressure interface 130 and transported throughnegative-pressure conduit 128 to the particulate filter 134. The fluidmay be filtered to remove particulate matter in the particulate filter134, before being recollected in the container 120.

In operation, the negative-pressure source 116 may pump fluid, such as asaline solution through the supply conduit 140 to a UV lightsterilization unit, such as UV light sterilizer 136. Once the fluid haspassed through the UV light sterilizer 136, the fluid may continuethrough supply conduit 140 to the ultrasonic bubble generator 138, wheremicro-bubbles may be generated in the fluid, followed by the fluid andmicro-bubbles being activated by ultrasonic energy applied by theultrasonic bubble generator 138. The activated fluid may then passthrough the fluid-delivery interface 142 and into the dressing 114. Theactivated fluid may then pass through the manifold 122 and reach thewound 104, where the activated fluid may debride necrotic tissue 112.

Following the debridement of the necrotic tissue 112 by the activatedfluid, the remaining effluent may be drawn out of the dressing 114 bynegative pressure applied to the dressing 114 and tissue site 102 by thenegative-pressure source 116. For example, the effluent may be drawnfrom the wound 104, through the manifold 122, and out of the dressing114 through the negative-pressure interface 130. The effluent may thenpass through negative-pressure conduit 128 to the particulate filter134, where particulate matter may be filtered out of the effluent. Thefiltered fluid may then be collected by the container 120 before beingrecirculated by the negative-pressure source 116 through the UV lightsterilizer 136 and ultrasonic bubble generator 138 to the wound 104.

The systems, apparatuses, and methods described herein may providesignificant advantages. For example, a therapy system described abovemay provide a low-pain, clean method to achieve an alternative form ofmechanical debridement. The therapy system can keep a wound enclosed,thus reducing the possible risk of infection, and can also store anyparticulate matter in a convenient location that may be easily disposed.The therapy system may also reduce the risk of contaminating theenvironment external to a wound with potentially infectious matter, andcan also keep odors contained.

While shown in a few illustrative embodiments, a person having ordinaryskill in the art will recognize that the systems, apparatuses, andmethods described herein are susceptible to various changes andmodifications. Moreover, descriptions of various alternatives usingterms such as “or” do not require mutual exclusivity unless clearlyrequired by the context, and the indefinite articles “a” or “an” do notlimit the subject to a single instance unless clearly required by thecontext.

The appended claims set forth novel and inventive aspects of the subjectmatter described above, but the claims may also encompass additionalsubject matter not specifically recited in detail. For example, certainfeatures, elements, or aspects may be omitted from the claims if notnecessary to distinguish the novel and inventive features from what isalready known to a person having ordinary skill in the art. Features,elements, and aspects described herein may also be combined or replacedby alternative features serving the same, equivalent, or similar purposewithout departing from the scope of the invention defined by theappended claims.

What is claimed is:
 1. An apparatus for debriding a tissue site,comprising: a dressing for placing on the tissue site; and an ultrasonicbubble generator fluidly coupled to the dressing and configured togenerate micro-bubbles and ultrasonic waves in a fluid delivered to thedressing.
 2. The apparatus of claim 1, wherein the ultrasonic bubblegenerator further comprises an ultra-violet light source configured togenerate and treat the fluid with ultra-violet light.
 3. The apparatusof claim 1, wherein the dressing comprises: a manifold adapted to beplaced proximate to the tissue site; and a drape adapted to be placedover the manifold.
 4. The apparatus of claim 3, wherein the manifoldcomprises a perforated felted foam.
 5. The apparatus of claim 4, whereinthe perforated felted foam comprises perforations in a range of 3-7millimeters (mm) in diameter.
 6. The apparatus of claim 1, furthercomprising a negative-pressure source.
 7. A micro-bubble system fortreating a tissue site, the micro-bubble system comprising: a gas bubblegenerator configured to inject micro-bubbles in a fluid from a fluidsource prior to the fluid entering the tissue site; and an acoustictransducer configure to transmit ultrasonic waves to the micro-bubblesin the fluid prior to the fluid entering the tissue site.
 8. Themicro-bubble system of claim 7, further comprising an ultra-violet lightsource configured to generate and treat the fluid with ultra-violetlight.
 9. The micro-bubble system of claim 8, wherein the ultra-violetlight source is fluidly coupled between the fluid source and the gasbubble generator.
 10. The micro-bubble system of claim 8, wherein thefluid comprises filtered effluent from the tissue site.
 11. Themicro-bubble system of claim 7, wherein the ultrasonic waves aretransmitted as intermittent pulses.
 12. The micro-bubble system of claim7, wherein the micro-bubbles each comprise a diameter in a range ofabout 15 micrometers to about 200 micrometers.
 13. The micro-bubblesystem of claim 7, wherein the fluid comprises a saline solution with asurfactant.
 14. A method for debriding necrotic tissue from a tissuesite, comprising: supplying a fluid from a fluid source to an ultrasonicbubble generator, the ultrasonic bubble generator comprising an acoustictransducer and a gas bubble generator; injecting micro-bubbles into thefluid with the gas bubble generator; generating ultrasonic waves in thefluid with the acoustic transducer prior to the fluid being delivered tothe tissue site to deform at least a portion of the micro-bubbles; anddelivering the fluid with micro-bubbles and ultrasonic waves to thetissue site.
 15. The method of claim 14, wherein the ultrasonic bubblegenerator further comprises an ultra-violet light source configured togenerate and treat the fluid with ultra-violet light.
 16. The method ofclaim 14, the method further comprising: applying a dressing to thetissue site; coupling the fluid source to the dressing; and deliveringthe fluid with the micro-bubbles and the ultrasonic waves to the tissuesite comprises delivering the fluid with the micro-bubbles and theultrasonic waves to the dressing.
 17. The method of claim 16, furthercomprising coupling a negative-pressure source to the dressing.
 18. Themethod of claim 14, further comprising: deforming the micro-bubbles withthe ultrasonic waves to generate a ripple at a gas/liquid surface of theat least a portion of the micro-bubbles.
 19. The method of claim 18,wherein the ripple is configured to exert a scrubbing action on asurface of the tissue site.
 20. The method of claim 18, wherein theripple generates a turbulence around the at least a portion of themicro-bubbles, drawing the micro-bubbles into cracks, crevices, anddeformities at the tissue site.